Antidiuretic hormone
Antidiuretic hormone (ADH) is a hormone produced in the hypothalamus and released by the posterior pituitary gland. Its main function is to regulate the body's water balance by controlling the amount of water reabsorbed by the kidneys.
ADH acts on the collecting ducts of the kidneys, increasing their permeability to water. This allows more water to be reabsorbed and returned to the bloodstream, reducing the production of urine and preventing excessive water loss from the body. On the other hand, when ADH levels are low, the collecting ducts become less permeable to water, leading to increased urine production and water excretion.
Aside from its role in regulating water balance, ADH also helps to regulate blood pressure by constricting blood vessels, which increases peripheral resistance and raises blood volume. It can also trigger the release of aldosterone, another hormone that promotes the reabsorption of sodium ions, further aiding in water retention.
Disorders related to ADH include diabetes insipidus, a condition characterized by the inability to concentrate urine and excessive thirst, and syndrome of inappropriate antidiuretic hormone secretion (SIADH), which causes excessive retention of water and low sodium levels in the blood.
Overall, ADH plays a crucial role in maintaining water balance and regulating blood pressure in the body.